Section 18.1
Equilibrium: A State of Dynamic Balance
Practice Test
1.
What is the equilibrium constant expression for the following reaction?
ClNO
2
+ NO ‹–› NO
2
+ ClNO
a.
K
eq
= [ClNO
2
][NO]/[NO
2
][ClNO]
b.
K
eq
= [ClNO
2
][ClNO]/[NO][NO
2
]
c.
K
eq
= [NO]
2
[ClNO]/[ClNO]
2
[NO]
d.
K
eq
= [NO
2
][ClNO]/[ClNO
2
][NO]
Hint
2.
What is the equilibrium constant expression for the following reaction?
H
2
+ I
2
‹–› 2HI
a.
K
eq
= [HI]
2
/[H
2
][I
2
]
b.
K
eq
= [H
2
][I
2
]/ [HI]
2
c.
K
eq
= [HI]
2
/[H]
2
[I]
2
d.
K
eq
= [2HI]/ /[H
2
][I
2
]
Hint
3.
What is the equilibrium constant expression for the following reaction?
PCl
5
‹–› PCl
3
+ Cl
2
a.
K
eq
= [PCl]
5
/[PCl]
3
[Cl]
2
b.
K
eq
= [PCl
5
]/[PCl
3
][Cl
2
]
c.
K
eq
= [PCl]
3
[Cl]
2
/[PCl]
5
d.
K
eq
= [PCl
3
][Cl
2
]/ [PCl
5
]
Hint
4.
What is the equilibrium constant expression for the following reaction?
2SO
3
‹–› 2SO
2
+ O
2
a.
K
eq
= [SO
2
]
2
[O
2
]/[SO
3
]
2
b.
K
eq
= [2SO
2
][2O]/[2SO
3
]
c.
K
eq
= 2[SO
2
]
2
[O
2
]/2[SO
3
]
d.
K
eq
= [SO
3
]
2
/[SO
2
]
2
[O
2
]
Hint
5.
What is the equilibrium constant expression for the following reaction?
N
2
+ 3H
2
‹–› 2NH
3
a.
K
eq
= [N
2
][H
2
]
3
/[NH
3
]
2
b.
K
eq
= [N
2
]
3
[H
2
]/2[NH
3
]
c.
K
eq
= [NH
3
]
2
/[N
2
][H
2
]
3
d.
K
eq
= 2[NH
3
]/ [N
2
]
3
[H
2
]
Hint
6.
When Δ G is zero, ______________.
a.
the reaction is spontaneous
b.
the reaction is not spontaneous
c.
the reaction is at equilibrium
d.
the reaction has no energy
Hint
7.
When the system A + B ↔ C + D is at equilibrium, ___________.
a.
the forward reaction has stopped
b.
the reverse reaction has stopped
c.
both the forward and reverse reactions have stopped
d.
neither the forward nor the reverse reaction has stopped
Hint
8.
A molecular system that is a dynamic process with two opposing reactions balancing each other is a(n) ___________.
a.
chemical equilibrium
b.
spontaneous reaction
c.
nonspontaneous reaction
d.
unreacted set of chemicals.
Hint
9.
What is the equilibrium constant expression for the following reaction?
4NH
3
(g) + 5O
2
(g) → 4NO(g) + 6H
2
O(g)
a.
K
eq
= [NH
3
] [O
2
]/[NO] [H
2
O]
b.
K
eq
= [NH
3
]
4
[O
2
]
5
/[NO]
4
[H
2
O]
6
c.
K
eq
= [NO]
4
/[NH
3
][O
2
]
d.
K
eq
= [NO]
2
[H
4
O]
6
/[NH
3
]
4
[O
2
]
5
Hint
10.
What is the equilibrium constant expression for the following reaction?
2NH
4
NO
3
(s) → 2NH
3
(g) + 2NO(g) + H
2
(g) + 2O
2
(g)
a.
K
eq
= [NH
3
][NO][H
2
][O2]
b.
K
eq
= [NH
3
]
2
[NO]
2
[H
2
][O2]
2
c.
K
eq
= ([NH
3
][NO][H
2
][O2])/[NH
4
NO
3
]
d.
K
eq
= ([NH
3
]
2
[NO]
2
[H
2
][O2]
2
)/[NH
4
NO
3
]
2
Hint
11.
For the reaction, 2A + B → C + 2D at 35°C, the value of the forward rate constant,
K
f, is 3.0 × 10
-3
M
-1
s
-1
and the value of the reverse rate constant,
K
r, is 1.5 × 10
-2
M
-2
s
-1
. Calculate the value of
K
eq
for this reaction.
a.
2
b.
0.5
c.
0.2
d.
5
Hint
12.
Consider the following reaction in which all reactants and products are gases. 1.00 mole of A and 2.00 moles of B are placed in a 5.0—L container. After equilibrium has been established, 0.50 mole of D is present. What is the equilibrium constant for this reaction: A + 2B → 2C + D?
a.
1
b.
0.15
c.
0.33
d.
3
Hint
13.
When will the least time be required for a reaction to reach equilibrium?
a.
K
eq
is very small
b.
K
eq
is very large
c.
K
eq
is approximately 1.00
d.
cannot tell because the time to reach equilibrium does not depend on
K
eq
Hint
